TN does not have copper nose in public waters. I do have access to a private lake and have caught a ton of them. They come in every color imaginable. We have one TWRA lake that has copper nose mixed with northern strain bluegill. All the copper nose I have caught....the pure ones and the mixed strain...all have the colored band across the forehead. I go by that band.....I have caught a ton of northern strain bluegill that are purple....so I don't think that is a true indicator of a copper nose.
Regards